As it seems now obligatory to mention anti-spam systems whenever a /. story mentions spam, I thought I'd add the following:

Please have a look at Spam Cannibal [spamcannibal.org]

It's an interesting concept that if correctly deployed (big "if") by even a relatively few admins around the world, could really make a difference to the amount of spam on the net. It can also protect hosts against DoS attacks of various kinds.

Don't get me wrong, I'm not astroturfing this (much...). It has flaws - there are those who think blacklisting is a bad idea, and I can see their point of view on that - but I just think Spam Cannibal needs more visibility as an approach.